Hitherto, metallic materials are broadly used as materials for mechanical parts due to their various excellent material characteristics. In these years, needs for mechanical parts are increasing as a result of advances in technologies. Specifically, mechanical parts using sintered ceramics, plastics or any other nonmetal materials are frequently used to cover shortcomings of metallic materials.
However, it is a current circumstance that conventional materials hardly cope with all of various needs in the progress of the technical innovation. Accordingly, there exists a demand for materials applicable to mechanical parts having novel characteristics.
In order to satisfy those demands, new materials are continuously developed. Under this trend, various techniques for forming a high-strength cured product by a hydraulic composition for the application to mechanical parts are proposed. For example, Japanese Patent Application Laid-open No. Sho-61-215239 discloses ultrahigh-strength mortar and concrete formed by a composition containing as main constituents a cementitious substance and ultrafine powder, high-range water reducing agent, water and aggregate. Japanese Patent Application Laid-open No. Sho-62-52157 discloses a high-strength cured product derived from the introduction of metallic particles into a cementitious admixture. Japanese Patent Application Laid-open No. Hei-03-137047 discloses a combined material of a cementitious substance and polymer. However, these cementitious cured products have yet put into practical use due to their poor strength and workability.
In order to address those problems, the present inventors made various studies and found that a molding produced by using a hydraulic composition resulted from the combination of a hydraulic powder, non-hydraulic powders having an average particle diameter of {fraction (1/10)} or less of that of the hydraulic powder, workability improver, moldability improver and the like possess exhibits an excellent property achieving the applicability to sheet-feeding rollers or any other mechanical parts. Consequently, they filed a patent application (Japanese Patent Application Nos. Hei-11-28137, and Hei-11-59310).
However, cured products of those hydraulic compositions must further improve the surface hardness for the application to mechanical parts requiring a higher wear resistance. Needs to mechanical parts are not only for wear resistance, but also for improved electric conductivity, magnetic property, electromagnetic wave shielding property, heat shielding property, and other various properties. Consequently, conventional moldings of hydraulic composition hardly satisfy these needs.